Check my log please

[SrKegler]

Finally got all my CEL's to clear and got a log. Not sure what you guys need to decipher how the engine is running. Car is stock except for 255 fuel pump and afpr. Fuel pressure set to 37#.

FTRL 137%
FTRM 116%
FTRH 134%

RPM 2906 - TIMA 33 deg - O2R O.60V

Cool - 186 deg, AIRT 68 deg

What I'm confused about is the fuel trims. I thought good readings were around 100%. I took these reading while on a 20 mile drive running around 60 MPH.

Thanks for any help.

 

[We're on Boost]

Hmm, is it a manual tranny, or automatic?
Is that fuel pressure with vac hose disconnected?

 

[SrKegler]

Manual transmission, vac hose off and plugged.

 

[Nvisabl]

You did re-hook vac. hose back up for the drive , right?

 

[SrKegler]

Yes, hose is hooked up. From what I've gathered using the search, the 1G shows 100% as a baseline. 137%, to me, means it's adding 37% more fuel. Just wondering if this is normal. I have no boost leaks, can not find any vacuum leaks, new plugs, wires, etc.

First time I've been able to clear up all the CELs the car had. Was just playing around with the logger and noticed the fuel trims which seem excessive.

 

[We're on Boost]

Do you have stock downpipe and cat on the car?
If so, I'll look at some of my old logs from when I had stock downpipe and cat.
You did the fuel pressure right for manual tranny car.
I can say right now, your numbers for O2 voltage and timing look just fine for light cruise conditions - guess you knew that already but just confirming.
The O2 voltage is consistent with closed loop rapid cycling and the timing is just like what my 1g does during light cruise conditions.
I agree about the fuel trims, doesn't seem like they should be high.
What really bugs me is they are all high - short term, mid term, and long term. I don't know what the mid and long term trims actually do, so we'll need some help in that area. I only log short term trim, and "O2 feedback trim" which kind of goes back and forth 180 degrees out of phase with the actual O2 voltage as I remember.

 

[doubleclutch99]

mid , low ,and high fuel trims are supposed to run at 100 % + or - 5 % and the ideal 02 v should cycle around .88 v . all of your numbers are pointing toward a lean condition.

 

[SrKegler]

mid , low ,and high fuel trims are supposed to run at 100 % + or - 5 % and the ideal 02 v should cycle around .88 v . all of your numbers are pointing toward a lean condition.

That's what has me puzzeled. Car is completely stock except for the fuel pump and AFPR. 02 seems to be working but I have seen it as low .07 at idle, .13 @ 1700 rpm, .48 at 4200, seems to cycle from .03 to .80 quite frequently.

 

[We're on Boost]

02 seems to be working but I have seen it as low .07 at idle, .13 @ 1700 rpm, .48 at 4200, seems to cycle from .03 to .80 quite frequently.

Well, you are just taking snap shots I think, with MMCd, right? You don't see a continuous graph of what the O2 voltage is doing. When you take a snapshot during any of these light load conditions that you mentioned, you are going to catch the O2 voltage at anywhere between about .03 and .8 volts because that is the normal cycle range.
Take a look at this little piece of a log on my car, when I had stock downpipe and cat and stock injectors. Cruising at about 50 mph. The horizontal axes are scaled to 2 seconds per division, so a whole window from left to right is 10 seconds. You can see the O2 voltage is cycling rapidly, about 3 or 4 cycles per second. O2 voltage ranges from about .03 up to about 0.75 volts. I have the mouse at the bottom of a cycle, the O2 voltage right there is only .04 volts. The Engine Monitor window shows the other logged values at that same instant. Throttle is light, 1.12 TPS volts. Timing 35 deg.
My Fuel Trim Low is steady at about 98%. And that is where yours is suspicious, the fuel trim.
I see that my "O2 Feedback Trim" was hovering around 140% during light cruise, and I don't really know what the significance of that is, except that it cycles rapidly like the O2 voltage.

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[SrKegler]

Thanks for that post. I've been doing some more searching and it looks like my BARO doesn't move, its stays at 14.3.

Vacuum leak somewhere or another bad sensor.

I'm not showing any codes now.

 

[We're on Boost]

Another good thing to know, Low (short term) trim can only go up to 140% max, that's as high as it will go (91-94 ecus).
In other words, 100% is no correction, 140% is a 40% correction richer.
So you are right about at the limit of what your ecu can correct for, I think.
But it does seem like it is correcting, because you are getting O2 voltages consistent with the O2 cycling like it should.
When the problem has gone beyond where the 140% can correct for it, then the O2 will flatline at 0 volts.
I have a log where I did that on purpose, in my idle and low load fuel map cells. I put in -12% in all those cells, in the ecuplus fuel map. That subtracted just enough to make my O2 flatline and peg the Low fuel trim at 140%. Here's a pic:

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In this log I have a 1994 ecu. I think the stock 1990 ecu will only go up to 120% fuel trim low.
Anyway yours is a 1992? so it should act like the 1994 in this pic.

I guess the real worry is, if your ecu is correcting about 38% richer while you are in closed loop, what is happening at WOT when you are open loop and the ecu can't correct for anything, except by knock counts! Which you can't hear! You have to be logging knock to know that you are knocking, pretty much.

 

[SrKegler]

The most knock I've logged is 1 count. I usually shift around 4-5000. Only problem I can see is BARO numbers don't get high enough to allow it to go into the "learn mode". Just worried about it running too lean and burning holes in the pistons. Only have another 4% correction left.

I've sprayed starting fluid everywhere I can think of and don't detect any change in the engine.

 

[We're on Boost]

Glad you aren't seeing big knock count numbers. You might see it though at higher rpm. Looking back on my logs, when I had stock exhaust and injectors, the highest knock counts I got were at stupid times like when I was hardly on the gas (like TPS 1.25 volts) and that I think is just engine noise. The real knock that you would worry about, at heavy throttle, I was pretty free of that until my MAS Hz started going over 1600. And that happened with the 3" downpipe - no cat - 3" exhaust, plus boost higher than stock. So that's when I put in the bigger injectors and so forth.

The FTRL number you posted, was at cruise. What kind of FTRL numbers do you see at idle?

The FTRL numbers at idle, since idle is the only condition where you know for sure what your fuel pressure is, could tell us something (I'm assuming you weren't able to look at your fuel pressure gauge while driving down the road).
If the fuel trim at idle is way high like it is at cruise, then I would suspect your 18 year old injectors are cloggy or just not flowing as much as they should. Or your MAS could somehow be way off, or the ecu could be bad, or anything else you could think of that would put too little gas through the injectors even though the fuel pressure is correct.
If the fuel trim at idle is normal ~ 100%, then I think you could take injectors off the suspect list. But you would have to add some other items to the list, like everything upstream from the fuel rail. You know, cloggy fuel filter, leaky or out-of-postion O-ring on the outlet of the fuel pump. Anything that would flow ok at very low flows but be restrictive to higher fuel flows. Or in the case of the fuel pump O-ring it wouldn't be restrictive, it would be bleeding fuel off back into the tank instead of sending it down the line. In other words your fuel pressure would be off at high flow rates, but normal at idle. If you are using the O-ring from the Walbro install kit that is a distinct possibility, because the O-ring in that kit is a little too small, and the spacer doesn't sit straight on the pump - it sits at a bit of an angle, because of some raised lettering on the surface of the pump. Pretty funky!

Or of course it could be a vacuum leak somewhere, since we are talking about running lean when you are off boost, low load. I don't think so though, that's a pretty big vacuum leak!

BTW there is a test for the Baro and IAT sensor in the Haynes manual on page 6-17. Supposedly a bad Baro will throw a code 25, bad IAT code 13, bad airflow sensor code 12, but I wouldn't count on it.

 

[We're on Boost]

Whaddyaknow, I found that fuel trim page I wanted to find, it's on the PocketLogger web site. Here are some excerpts:

"A dead or slow O2 sensor will wreak havoc on your trims. High values for all three trims (indicating a lean condition) are a good indication that your O2 is dead."

"An abnormally high Low Fuel Trim is a good indication that the heater in O2 sensor is dead. Most of the time, during idle, the O2 sensor will stop cycling after sitting for a minute or so. This is a good indication that the heater is indeed dead."

"The O2 trim is derived from comparing the actual O2v to what the ECU thinks the O2 should be (stoichiometric). The idea is to keep the O2 trim right. If there is a trend (lean or rich) in the O2 trim for a period of time, it is corrected via the appropriate (high, med, low) trim. Which trim is adjusted is based on the current airflow. This will allow the O2 trim to go back to its midpoint because one of the other trims is making the fuel delivery correction."

http://www.pocketlogger.com/index.php?pid=1gtech_trims

In that last quote I think "O2 trim" is what I've been calling "O2 feedback trim" and therein lies my confusion about the different trims, because people aren't consistant about how they name them. But I think I've got it now, sort of.
Together with what Steve linked to in the ECM wiki:

http://www.dsmlink.com/wiki/fueltrimupdatepoints?s=trims

and the "all must be true" list for 1g learn mode that Steve also posted, which I think you've already seen:
Coolant temp >= 190F
Intake air temp < 123F
Baro >= 22.9 inHg
Baro <= 31.6 inHg

 

[SrKegler]

Thanks for all the help. Water pump went out on me yesterday so I now have different priorities. A bad 02 sensor makes perfect sense. During the logs it seemed to be cycling.

Another quick question though, my BARO readings are always 14.2 or 14.3. Doesn't look like ever meets to parameters for "learn" cycle. Does a bad 02 affect that reading or do I have another bad wire in hte MAF plug.

 

[We're on Boost]

Thanks for all the help. Water pump went out on me yesterday so I now have different priorities. A bad 02 sensor makes perfect sense. During the logs it seemed to be cycling.

Another quick question though, my BARO readings are always 14.2 or 14.3. Doesn't look like ever meets to parameters for "learn" cycle. Does a bad 02 affect that reading or do I have another bad wire in hte MAF plug.

Well, if that 14.2 is psi, it converts to 28.91 inches of mercury, and that would be right smack in the range. That also is a reasonable atmospheric pressure in most places that are just slightly above sea level. So I would say you have to figure out somehow if MMCd is giving you psi, or what.
In post 18 in this thread: http://www.dsmtuners.com/forums/tuning-engine-management/369994-datalogging-issues-need-help.html Steve says to go into the MMCd options menu to set units to English - do you have that? - there must be some MMCd documentation that tells you what the unit is that they give you for that baro number. Or Steve would probably know, he seems to know a heck of a lot about MMCd. If the 14.2 number is inHg then yeah, the ecu would not be updating those trims.

I don't know if a bad O2 would affect the baro reading. I wouldn't think so. The test in the Haynes manual for IAT and BARO is pretty simple, you would need a meter to measure volts and ohms.
Dang, did you actually have a bad wire to the MAF plug? or was it the little terminal in the plug that was bad? I had a bad terminal in the plug to my power transistor once and it caused all kinds of trouble until we figured out what it was. I wish all these plugs were available brand new, I would replace most of them. Bad electrical plugs was part of the reason I did the rewire/relocate of my ecu.


Man I'm glad we went through all this stuff because I learned things I had been wondering about too.
For one thing, I thought that "short term fuel trim" and "O2 feedback trim" were 2 different things. But they are just 2 different names for the same thing. I'm going to continue to call it "O2 feedback trim" because that's how my logger labels it. But other logging systems and other people name it differently. The word "feedback" works for me, because in electronic systems, feedback is usually very fast or instant. And the O2 Feedback Trim does basically cycle right along with the O2 voltage in closed loop, it is fast. Then the other 3 trims (Low, Mid, High) are all "long term trims", just in different air flow ranges.

 

[SrKegler]

I had a bad terminal in the plug. Word of warning, those are almost impossible to get out. I finally fabricated a super small brush and cleaned the old one up. Then squished the top down some and pried the sides in. Guess it was just corrosion.

Well back to replacing that fabously designed water pump.

 

[We're on Boost]

Sounds about right on that electrical plug.

Ha, yeah the water pump will be fun.